testsuite: mark T7919 as fragile on i386 as well
T7919 may also fail i386 CI jobs with test timeout. One recent example in a marge pipeline: https://gitlab.haskell.org/ghc/ghc/-/jobs/1799462 Related issue: #22283
T7919 may also fail i386 CI jobs with test timeout. One recent example in a marge pipeline: https://gitlab.haskell.org/ghc/ghc/-/jobs/1799462 Related issue: #22283